June 1990 - Vol. 33 No. 6
Features
Evaluation of safety-critical software
Methods and approaches for testing the reliability and trustworthiness of software remain among the most controversial issues facing this age of high technology. The authors present some of the crucial questions faced by software programmers and eventual users.
Disaster recovery planning for academic computing centers
Planning for recovery from a disaster is quickly becoming recognized as a necessity for higher education computing installations. This article presents a structural framework, describes the stages, and tells how to implement a disaster recovery plan specifically geared to an academic computing organization.
Departmentalization in software development and maintenance
Exploring the strengths and weaknesses of three alternative bases for systems staff departmentalization suggests the benefits of an organizational form in which maintenance is separate from new system development.
Skip lists: a probabilistic alternative to balanced trees
Skip lists are data structures that use probabilistic balancing rather than strictly enforced balancing. As a result, the algorithms for insertion and deletion in skip lists are much simpler and significantly faster than equivalent algorithms for balanced trees.
Fast hashing of variable-length text strings
Using only a few simple and commonplace instructions, this algorithm efficiently maps variable-length text strings small integers.
Concurrent operations on extendible hashing and its performance
Extendible hashing is a dynamic data structure which accommodates expansion and contraction of any stored data efficiently. In this article, an algorithm has been developed for managing concurrent operations on extendible hashing by achieving optimal memory utilization by supporting directly expansion and contraction, page split, and merge. The results of this study have been encouraging in the sense that it seems to provide a higher degree of concurrency compared to other algorithms on an extendible hash file.
